Much of today's modern Ethernet infrastructure is based on twisted pair copper cables that meet certain specifications. One common “category” of Ethernet cable is identified as CAT5e, which is rated for data rates up to 1 Gbps. Recently, however, proposals have been made to use the existing Ethernet infrastructure in the enterprise environment for data rates above 1 Gbps and up to 5 Gbps and beyond. Using cabling such as CAT5e at higher rates poses challenges, especially when affected by alien crosstalk.
In order to operate at such high data rates in relatively noisy environments, training sequences are often employed to characterize Ethernet link parameters and ensure that the link partners can transmit and receive data at the specified high data rates. Information may be exchanged between the link partners before the link can go online through an Infofield protocol that is utilized during a training mode of operation. The exchange protocol is typically disabled once the specified training sequence is complete.
In some situations, it would be desirable to exchange information, such as alien crosstalk information, between link partners following completion of the training mode of operation, but before the link can go online for high-speed data transfers.